“J.J. McCarthy could be the Vikings’ starting quarterback at the beginning of his rookie season, but it largely depends on his performance. The team isn’t in a rush to start him, especially since they have new $10 million bridge option Sam Darnold to begin the year as QB1. However, the 21-year-old McCarthy has the chance to prove himself during spring practices, training camp, and preseason games. Head coach Kevin O’Connell’s decision for Week 1 will be based on how McCarthy and Darnold perform during the offseason.” O’Connell and Vikings GM…